Developing biofuels continues to be a bright spot in the cleantech world. Two startups, plant genetic engineering company Chromatin and biofuel producer ZeaChem, announced separately on Tuesday that they have raised new rounds of funding.  Chicago-based Chromatin said it has lined up $10 million – the first close of the D round – from investors including the venture arm of oil giant BP and the investing arm of product firm Unilever. Chromatin has developed a technology to genetically modify energy crops so that they grow fast and abundant, and its plant of choice if sorghum, a grass with some desirable, natural characteristics as a bioenergy feedstock, such as a high tolerance for drought and heat.